Luminaires, such as down lights or the like, may include a can and a light engine disposed within a cavity defined by the can. The light engine includes a light source configured to generate light. One such type of light source includes light emitting diodes, LEDs. While LEDs may generate less thermal energy compared to traditional bulbs (e.g., incandescent light bulbs), LEDs nevertheless generate thermal energy which should be managed in order to control the junction temperature. A higher junction temperature generally correlates to lower light output, lower luminaire efficiency, and/or reduced life expectancy. Unfortunately, managing thermal energy is particularly challenging when designing ceiling fixtures because temperature gradients in a room send the hottest air closest to the ceiling. Moreover, thermal insulation installed in the ceiling, and particularly proximate to the ceiling fixture, may reduce and/or suppresses natural convection. For example, the thermal insulation may have a thermal conductivity of approximately 0.04 W/(m−K), and as a result, the thermal insulation may generally only permit the removal of thermal energy upward from the ceiling fixture by thermal conduction which occurs at a far slower rate than thermal convection above the ceiling.
Another challenge facing the design of ceiling fixtures involves a plurality of ceiling fixtures installed throughout a room. In particular, the ceiling fixtures which are surrounded by other ceiling fixtures (e.g., ceiling fixtures in the middle of the room) are most vulnerable to overheating as they are farthest from the walls (which may help to act as a heat sink). Moreover, nearby ceiling fixtures generate thermal energy which reduces and/or minimizes any lateral temperature gradient across the ceiling. As a result, thermal energy is generally limited to upward and downward. Because hot air rises, most of the thermal energy must travel through the insulated ceiling.